Analysis of solid concentration distribution in dense solid–liquid stirred tanks by electrical resistance tomography

• Spatial solids distribution in solid–liquid stirred tanks is investigated.
• ERT is applied to measure solid concentration in dense suspensions.
• The effect of the solid loadings on the mixing quality is quantified.
• A novel parameter is suggested for the suspension homogeneity evaluation.

The knowledge of the spatial solids distribution is important for predicting the performance of various processes carried out in mechanically stirred equipment. In this work, the solid suspension in a stirred tank equipped with PBT and Lightnin A310 impellers is investigated by electrical resistance tomography (ERT). The analysis concerns dense solid–liquid systems, with mass ratio of suspended solid to liquid up to 0.43, with the main goal of obtaining detailed information on the spatial distribution of the dispersed phase and on the mixing quality. The shape of the interface between the solid mixture and the clear liquid layer is also determined. The results provide insight into the complex behaviour of dense suspensions and can be adopted as a benchmark for advanced modeling techniques based on CFD methods.Based on the experimental results, a method for the evaluation of the distribution of the solids under different working conditions and geometrical set-up is suggested. This criterion can provide a guideline for scale-up, when equal solid distribution at different scales is required.